A treatment review can show where research exists without establishing which treatment works best. Hersi and colleagues’ 2023 scoping review of problematic methamphetamine use illustrates that distinction. Its evidence maps identified potentially favorable findings across many interventions, but the authors did not present those maps as reliable treatment rankings.
What did the review include?
The review identified two systematic reviews, one clinical practice guideline and 54 primary controlled studies reported in 69 publications. Those are different units. Several articles can describe one study, and a systematic review can include trials also discussed elsewhere. Adding all publications together would exaggerate the number of independent tests.
The updated searches ran through February 2022. Eligible primary studies addressed methamphetamine use disorder or problematic methamphetamine use, with rules for separating relevant participants from broader stimulant samples. Most outcomes required follow-up of at least three months. The review excluded certain approaches, including exercise, transcranial magnetic stimulation and art therapies. Its map therefore was not a census of every possible intervention.
What did a favorable direction mean?
For the primary-study synthesis, the team used vote counting by direction of effect. A result could favor intervention or comparison, show no difference, or remain unclear. Crucially, classification did not incorporate statistical significance, effect magnitude or differences in study sample size.
A small favorable estimate with substantial uncertainty could therefore point in the same direction as a large, precise benefit. The authors explicitly warned that a direction alone might represent a clinically unimportant difference. Counting favorable directions cannot tell a reader how many people benefit, how much outcomes improve, or how confidently a difference excludes chance.
Why were the treatments difficult to compare?
The review identified 37 approaches to measuring methamphetamine use. An intervention could look favorable on one measure and less favorable on another. Studies also differed in intervention delivery, comparators, populations and assessment schedules.
Even apparently similar abstinence outcomes could require different numbers of submitted negative urine samples. A person meeting a less demanding specimen rule is not necessarily comparable to someone meeting a stricter rule in another trial. Treatment retention, reduced use, craving and abstinence are related but distinct outcomes.
These differences also affected the feasibility of network meta-analysis. Such an analysis needs more than a connected diagram of treatments: the studies must support sufficiently credible comparisons. The authors judged the available evidence unsuitable for robust network meta-analyses.
What quality checks were performed?
The researchers appraised systematic reviews with AMSTAR-2 and the guideline with AGREE-2. They did not assess the quality of individual primary studies, consistent with their scoping approach. A colorful primary-study evidence map should not be read as though each contributing trial had passed a uniform risk-of-bias assessment.
The review also found sparse information for several priority populations, including pregnant people and people in correctional settings. English- and French-language restrictions, differences in reporting and single-study interventions further limited coverage and certainty.
How can the map be used responsibly?
It is useful for locating research, identifying neglected populations and choosing studies for closer appraisal. It is weaker support for statements that one treatment is definitively superior or that nearly every intervention is effective because at least one result points in a favorable direction.
For an individual treatment claim, the next task is to examine the original comparison, endpoint, effect size, uncertainty, missing data and harms. This review describes evidence available through its search period; it does not supply current prescribing guidance or replace a direct assessment of a particular trial.
Source
Hersi M, Corace K, Hamel C, et al. Psychosocial and pharmacologic interventions for problematic methamphetamine use: Findings from a scoping review of the literature. PLOS ONE. 2023;18(10):e0292745. doi:10.1371/journal.pone.0292745.
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